DorinDXN
Posts: 3085
Location: Timisoara, Romania
Registered: 14 Nov 2006
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A way to shoot - fisheye 6 around
Posted: 3 Jul 2007 at 14:11 GMT
updated: 3 Jul 2007 at 14:22 GMT
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Hi, I know.., Idon't have fisheye and may not be the one to post such tricks but I'm using my imagination and maybe some of you are kind enough to put this in practice and fine tune for benefits of all.
I make a picture because a picture worth 5000 words, is not a typo, in case of my English 
so you need a fisheye mirror on simple rigg (cheap tripod or simple stative) that kind of mirror which is in small shops and allow to the owner to see what's moving, mirror for bicyle or so .. that mirror is puted very near to the camera, don't worry of parallax, the parallax shift will affect only the mirrors border and not it's distant reflected content, don't worry but keep that in mind!
The photos featuring the mirror have a M in label, so one can see that we have two of 5M, which must be merged,
For control points the
1,2,3,4, the_merged_5M and 6M
will be used, and for final stitch, of course the photos without M, mean
1,2,3,4,5,6
Remote is, obviously necessary and the method is suitable for static scene.
hope this helps,
Dorin
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DorinDXN
Posts: 3085
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: A way to shoot - fisheye 6 around
Posted: 3 Jul 2007 at 15:53 GMT
updated: 3 Jul 2007 at 16:02 GMT
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Hi again, as a variant you can change the mirror with more mirrors (not fisheye, the regural, small in a structure which to permit to control where you want to have reflected CP, or with a magnifying glass, then you'll have a an extra inserted upside-down image instead of mirrored back, anyway, don't be tempted to put simply plain a tabel with points unless you are pretty sure that you have no parallax or your setup is sturdy enough to not have induced parallax due to some play in setup.
Still at some distance some big tabel with CP ,customised, black on white  might work, though
Dorin
p.s. magnifying glass seems that is need to be (at) too big (distance) to work, so abort that way please
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John Houghton
Posts: 3710
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: A way to shoot - fisheye 6 around
Posted: 3 Jul 2007 at 16:51 GMT
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Dorin, Your idea is not unlike one I had for using a mirror (or mirrors) to provide distant features at the nadir when calibrating lens parameters with a 380x180 in a large building. You want features a long way away to avoid any parallax effects, but the floor is generally too close to provide such features. Putting a mirror on the floor provides features reflected from far above the camera.
I think the weakness in your scheme is the repeatability of yaw settings for the shots taken with and without the mirror. You need to use a head with detents. But in that case, you can calibrate the head to determine the yaw values at each setting so a mirror isn't really necessary. Pitch and roll are known values from neighboring images.
John
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DorinDXN
Posts: 3085
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: A way to shoot - fisheye 6 around
Posted: 3 Jul 2007 at 16:58 GMT
updated: 3 Jul 2007 at 17:03 GMT
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John Houghton said: I think the weakness in your scheme is the repeatability of yaw settings for the shots taken with and without the mirror. You need to use a head with detents. But in that case, you can calibrate the head to determine the yaw values at each setting so a mirror isn't really necessary. Pitch and roll are known values from neighboring images.
John, is not the case, I sugested to put the mirror in front and shoot, please follow the sequence of taking the pictures, I don't use detents anyway (they not need in that case), maybe I should care more about my explanation and better words.
Please study again the sequence of the photos.
is no move of the camera bettween appearence and disappearance of the mirror (ie 4 and 4M, 5 and 5M)
thanks,
Dorin
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John Houghton
Posts: 3710
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: A way to shoot - fisheye 6 around
Posted: 3 Jul 2007 at 17:23 GMT
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Dorin, Sorry. Yes, I see now how it works. I should have been more patient with the animated graphic. I can see that it could be a useful technique on occasion, but for really featureless areas, I still think detents are a simpler solution.
John
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DorinDXN
Posts: 3085
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: A way to shoot - fisheye 6 around
Posted: 3 Jul 2007 at 17:24 GMT
updated: 3 Jul 2007 at 17:37 GMT
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Maybe is better in this way,
The sequence is:
1) Take Photo [1]
2) move to next yaw
3) Take Photo [2]
4) move to next yaw
5) Take Photo [3]
6) move to next yaw
7) Take Photo [4]
8) put the mirror in front
9) Take Photo [4M]
10) move to next yaw
11) Take Photo [5M]
12) remove the mirror
13) Take Photo [5]
14) put the mirror in front for the other seam
15) Take Photo [5M] the second 5M
16) move to next yaw
17) Take Photo [6M]
18) remove the mirror
19) Take Photo [6]
thanks,
Dorin
p.s. I wrote this while you posted, thanks again John.
also a errata is needed
for setting the control points the photos used are
1,2,3,4M,merged_5M,6M
D.
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jeffE
Posts: 73
Location: Chicago, United States
Registered: 23 Mar 2007
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Re: A way to shoot - fisheye 6 around
Posted: 24 Aug 2007 at 13:49 GMT
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Sorry, I may b e dense here - WHAT is "CP" ??!
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DorinDXN
Posts: 3085
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: A way to shoot - fisheye 6 around
Posted: 24 Aug 2007 at 14:27 GMT
updated: 24 Aug 2007 at 14:27 GMT
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Hi, I used CP for Control Points, mean details suitable for placing the control points, for example, when you have in one part a building and in opposite an open area featuresless, or indoor featuresless walls.
Dorin
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